I hear the NOAA forecast provide the estimated location of the GS as in X NM east of certain locations. Using that info it one can plot it, and then as implied by FSMIKE use your GPS. However other than that, it seems like pure observation.
In South Florida the water color changes once you leave the 20-40' depths and enter the 500' depths 3 NMs out. Yet, I assume that is still not the GS. Am I correct?